Influence of z-pinning on the buckling of composite laminates under edge-wise compression

Z-pinning is a newly developed technique to enhance the strength of composite laminates in the thickness direction. Recent experimental and theoretical studies have shown that z-pins significantly improve mode I and mode II fracture toughness. In practice, buckling accompanying delamination is a typical failure mode in laminated composite structures. For a complete understanding of the z-pinning technique towards improvements of the overall mechanical properties of laminated composites, a numerical model is developed in this paper to investigate the influence of z-pins on the buckling composite laminates with initial delaminations under edge-wise compression. The numerical results indicate that z-pinning can indeed effectively increase the compressive strength of the composite laminates provided that the initial imperfection is within a certain range. The magnitude of the improvement is consistent with available experimental data.

Numerical study of the mode I delamination toughness of Z-pinned laminates

A finite element (FE) model is developed to investigate mode I delamination toughness of z-pin reinforced composite laminates. The z-pin pullout process is simulated by the deformation of a set of non-linear springs. A critical crack opening displacement (COD) criterion is used to simulate crack growth in a double-cantilever-beam (DCB) made of z-pinned laminates. The toughness of the structure is quantified by the energy release rate, which is calculated using the contour integral method. The FE model is verified for both unpinned and z-pinned laminates. Predicted loading forces from FE analysis are compared to available test data. Good agreement is achieved. Our numerical results indicate that z-pins can greatly increase the mode I delamination toughness of the composite laminates. The influence of design parameters on the toughness enhancement of z-pinned laminates is also investigated, which provides important information to optimise and improve the z-pinning technique.

Mode II delamination toughness of Z-pinned laminates

Mode II delamination toughness of z-pin reinforced composite laminates is investigated using finite element (FE) method. The z-pin pullout process is simulated by the deformation and breakage of non-linear springs. A critical shear stress criterion based on linear elastic fracture mechanics is used to simulate crack growth in an end-notched-flexure (ENF) beam made of z-pinned laminates. The mode II toughness is quantified by the potential energy release rate calculated using the contour integral method. This FE model is verified for an unpinned ENF composite beam. Numerical results obtained indicate that z-pins can significantly increase the mode II delamination toughness of composite laminate. The effects of design variables on the toughness enhancement of z-pinned laminates are also studied, which provides an important technological base and useful data to optimize and improve the z-pinning technique.

An autonomous trimming system of large glass fiber reinforced plastics parts using an omni-directional mobile robot and its control

This paper describes an automated trimming system of large glass fiber reinforced plastic (GFRP) using an omni-directional wheeled mobile robot (WMR) and its path control method. In trimming GFRP parts, much glass fiber and plastic powder dust occur and it becomes bad visible in environment. It is necessary to correct dead-reckoning errors of the WMR in order to control its moving path. We have discussed an external correction method of the dead-reckoning errors for the WMR using ultrasonic sensor.

Experimental study on effect of loading rate on mode I delamination of z-pin reinforced laminates

This paper presents an experimental investigation on mode I delamination of z-pinned double-cantilever-beams (DCB) and associate z-pin bridging mechanisms. Tests were performed with three types of samples: big-pin with an areal density of 2%, small-pin with an areal density of 2% and small-pin with an areal density of 0.5%. The loading rates for each type of samples were set at 1 mm/min and 100 mm/min. Comparison of fracture load under different loading rates shows the rate effects on delamination crack opening and delamination growth. Optical micrographs of z-pins after pullout were also presented to identify the bridging mechanisms of z-pins under different loading rates.

Cement composites reinforced with surface modified coir fibers

An experimental investigation of coir mesh reinforced mortar (CMRM) is conducted using nonwoven coir mesh matting. The main parameters in this study are the fiber volume fraction (number of mesh layers) and fiber surface treatment with a wetting agent. The composites are subjected to the four-point bending test. The short-term mechanical properties of CMRM are discussed. Scanning electron micrograph analysis is used to observe the fiber—matrix interfacial characteristics. The results indicate that the addition of coir mesh to mortar significantly improves the composite post-cracking flexural stress, toughness, ductility, and toughness index, compared to plain mortar materials. The Albatex © FFC wetting agent (2-ethylhexanol) can effectively improve water absorption of coir fiber and enhance the fiber—matrix bonding strength. These coir mesh reinforced composites may be useful in civil engineering applications.

Motivational processes associated with unhealthy body change attitudes and behaviours

Objective
The relationship between approach–avoidance motivational processes and unhealthy body change attitudes and behaviours was investigated.
Method
Self-reported sensitivity to rewards (SR) and sensitivity to punishments (SP) were measured for a convenience sample of 130 women, aged 18 to 40 years, along with measures of disordered eating symptomatology and exercise dependence.
Results
Together, SR and SP significantly predicted variance in drive for thinness (21%), bulimia (17%), and obligatory exercise (7%). These relationships were partly mediated by internalization of the thin ideal, body comparison, and subjective importance of achieving one's ‘ideal’ body and of avoiding one's ‘worst possible’ body. Interestingly, body dissatisfaction partly mediated the relationships involving SP but not SR.
Discussion
The results suggest that an underlying sensitivity to punishments, but not rewards, can manifest as a ‘fear of fatness’. Both of these motivational traits can increase the salience of self evaluations, and thus indirectly contribute to unhealthy body change attitudes and behaviours.

Mechanical properties and energy absorption of ceramic particulate and resin-impregnation reinforced aluminium foams

The mechanical properties of aluminium foams can be improved by matrix reinforcement and resin-impregnation methods. In the present study, aluminium foams were reinforced by both ceramic particulate reinforcing of the aluminium matrix and resin-impregnating pores. The mechanical properties and the energy absorption of the reinforced aluminium foams were investigated by dynamic and quasi-static compression. Results indicated that the ceramic particle additions of CBN, SiC and B4C in aluminium foams increase the peak stress, elastic modulus and energy absorption of the aluminium foams, under both conditions of dynamic and quasi-static compression. Moreover, the aluminium foams with and without ceramic particle additions exhibited obvious strain rate sensitivity during dynamic compression. Furthermore, the resin-impregnation improves the mechanic properties and energy absorption of aluminium foams significantly. However, aluminium foams with resin-impregnation showed negligible strain rate sensitivity under dynamic compression. It is reported that both the ceramic particle addition and resin-impregnation can be effective techniques to improve the mechanical and the energy absorption properties of aluminium foams.

Personality, behavioural and affective characteristics of hazardous drinkers

The aim of this study was to investigate the influence of appetitive and aversive motivation on hazardous drinking behaviour by drawing on Reinforcement Sensitivity Theory (RST). A between-groups design examined differences between hazardous drinkers and matched controls on self-report and behavioural appetitive and aversive motivation. The relationship between motivational processes and changes in affective states following behavioural task performance was also examined. Data from 27 hazardous drinkers (M = 21.88 years, SD = 3.29) and 27 gender and age matched controls (M = 21.85 years, SD = 4.08) were utilised. The Card Arranging Reward Responsivity Objective Test (CARROT) assessed behavioural appetitive motivation and the computerised Q-TASK provided an index of behavioural aversive motivation. Self-report appetitive and aversive motivation was measured using the Sensitivity to Punishment and Reward Questionnaire (SPSRQ). Brief scales tapping state positive and negative affect were also administered. Hazardous drinkers were significantly higher than controls on self-report but not behavioural measures of appetitive motivation. Results also indicated that hazardous drinkers reported significantly higher levels of negative affect. These data suggest that hazardous drinkers are characterised by high trait appetitive motivation and state negative affect. It was suggested that RST may provide a useful framework for understanding both the appetitive and aversive motivational processes involved in drinking behaviour.

Incongruence between nurses' and patients' understandings and expectations of rehabilitation

Aims and objectives. To explore nurses' understandings and expectations of rehabilitation and nurses' perceptions of patients' understandings and expectations of rehabilitation.
Background. Within the context of a broadening appreciation of the benefits of rehabilitation, interest in the nature of rehabilitation is growing. Some believe that rehabilitation services do not adequately meet the needs of patients. Others are interested in the readiness of patients to participate in rehabilitation.
Design. Qualitative.
Method. Grounded theory using data collected during interviews with nurses in five inpatient rehabilitation units and during observation of the nurses' everyday practice.
Findings. According to nurses working in inpatient rehabilitation units, there is a marked incongruence between nurses' understandings and expectations of rehabilitation and what they perceive patients to understand and expect.
Conclusion. Given these different understandings, an important nursing role is the education of patients about the nature of rehabilitation and how to optimise their rehabilitation.

Relevance to clinical practice. Before patients are transferred to rehabilitation, the purpose and nature of rehabilitation, in particular the roles of patients and nurses, needs to be explained to them. The understandings of rehabilitation that nurses in this study possessed provide a framework for the design of education materials and orientation programmes that inform patients (and their families) about rehabilitation. In addition, reinforcement of the differences between acute care and rehabilitation will assist patients new to rehabilitation to understand the central role that they themselves can play in their recovery.

Phytophthora cinnamomi and Australia’s biodiversity : impacts, predictions and progress towards control

Phytophthora cinnamomi continues to cause devastating disease in Australian native vegetation and consequently the disease is listed by the Federal Government as a process that is threatening Australia’s biodiversity. Although several advances have been made in our understanding of how this soil-borne pathogen interacts with plants and of how we may tackle it in natural systems, our ability to control the disease is limited. The pathogen occurs widely across Australia but the severity of its impact is most evident within ecological communities of the south-west and south-east of the country. A regional impact summary for all states and territories shows the pathogen to be the cause of serious disease in numerous species, a significant number of which are rare and threatened. Many genera of endemic taxa have a high proportion of susceptible species including the iconic genera Banksia, Epacris and Xanthorrhoea. Long-term studies in Victoria have shown limited but probably unsustainable recovery of susceptible vegetation, given current management practices. Management of the disease in conservation reserves is reliant on hygiene, the use of chemicals and restriction of access, and has had only limited effectiveness and not provided complete control. The deleterious impacts of the disease on faunal habitat are reasonably well documented and demonstrate loss of individual animal species and changes in population structure and species abundance. Few plant species are known to be resistant to P. cinnamomi; however, investigations over several years have discovered the mechanisms by which some plants are able to survive infection, including the activation of defence-related genes and signalling pathways, the reinforcement of cell walls and accumulation of toxic metabolites. Manipulation of resistance and resistance-related mechanisms may provide avenues for protection against disease in otherwise susceptible species. Despite the advances made in Phytophthora research in Australia during the past 40 years, there is still much to be done to give land managers the resources to combat this disease. Recent State and Federal initiatives offer the prospect of a growing and broader awareness of the disease and its associated impacts. However, awareness must be translated into action as time is running out for the large number of susceptible, and potentially susceptible, species within vulnerable Australian ecological communities.

Family physical activity and sedentary environments and weight change in children

Objective. To examine associations between family physical activity and sedentary environment and changes in body mass index (BMI) z-scores among 10-12-year-old children over three years.
Method. Design. Longitudinal (three-year follow-up). Subjects. In total, 152 boys and 192 girls aged 10-12 years at baseline.
Measurements. Measured height and weight at baseline and follow-up (weight status, BMI z-scores); aspects of the family physical activity and sedentary environment (parental and sibling modelling, reinforcement, social support, family-related barriers, rules/restrictions, home physical environment) measured with a questionnaire completed by parents at baseline.
Results. At baseline, 29.6% of boys and 21.9% of girls were overweight or obese, and mean (standard deviation, SD) BMI z-scores were 0.44 (0.99) and 0.28 (0.89), respectively. There was a significant change in BMI z-score among girls (mean change=0.19, SD=0.55, p<0.001), but not boys. Among boys, the number of items at home able to be used for sedentary behaviour (B=0.11, p=0.037) was associated with relatively greater increases in BMI z-score. Among girls, sibling engagement in physical activity at least three times/wk (B=-0.17, p=0.010) and the number of physical activity equipment items at home (B=-0.05, p=0.018) were associated with relatively greater decreases in BMI z-score.
Conclusion. Sibling physical activity and environmental stimuli for sedentary behaviours and physical activity within the home may be important targets for prevention of weight gain during the transition from childhood to adolescence.

Cue reward salience predicts craving in response to alcohol cues

Many studies have shown that regular drinkers react to alcohol-related stimuli (i.e., cue reactivity) with a variety of appetitive responses, in particular, increased urge to drink. Recent research has focused on accounting for variability in responses to alcohol-related stimuli by examining drinking histories and personality. The aim of the current study was to extend this line of work by investigating the role of reinforcement expectancies (‘cue reward salience’) in alcohol cue reactivity research. In this study, ‘cue reward salience’ refers to the notion that appetitive responses will only ensue if the individual finds the stimulus to be equal to or more rewarding than initial expectations. Sixty-one regular drinkers completed a standard cue reactivity assessment whereby reactions (i.e., urge to drink and affect) to the sight, smell and taste of alcohol are measured and compared to a control condition. Results indicated significant increases in positive urge to drink but no changes in affect. Analyses revealed that drinking level and trait reward sensitivity were significant predictors of the urge to drink response. In addition, ‘cue reward salience’ accounted for significant additional variance in predicting urge to drink alcohol. Discussion focuses on the importance of measuring reinforcement expectancies when conducting cue reactivity studies.

Addressing evidence treatment gaps for cardiovascular disease through primary care collaboration

Aims & Rationale/Objectives
The aim is to establish the frequency of counselling by general practitioners (GPs) and community pharmacists (CPs) for patients with uncontrolled CVD risk factors. This will identify conditions for which CPs might collaborate with GPs in addressing evidence-treatment gaps.

Methods
A population survey undertaken in the Wimmera region of Victoria in 2006. 1425 adults aged 25-84 yrs were randomly selected using age/sex stratified electoral role samples. A representative 723 participants were recruited.

Principal Findings
Data on GP and CP visits were available for 694 participants. Overall, participants visited GPs 4.6 times and CPs 6.0 times/annum. However, one third of participants never consulted a pharmacist in 12 months compared to just 11.5% for GPs. Among obese patients (BMI ?? 30), the average number of visits/annum was 4.5 to GPs and 6.8 to CPs. The equivalent numbers were 5.6 and 8.6 respectively for those with systolic BP ?? 140 mmHg; 3.7 and 5.5 for total cholesterol > 5.0 mmol/L; and, 6.7 and 14.6 for patients with random blood glucose concentrations ?? 7.0 mmol/L.

Implications
People with suboptimal status for most common CVD risk factor are counselled frequently by CPs. A coordinated approach with GPs to the delivery of cardiovascular health promotion could provide valuable reinforcement of key messages and offers greater opportunity to identify at-risk individuals. Acknowledgements: KM is a pharmacist-academic at Greater Green Triangle UDRH, a position funded by the Department of Health and Ageing through the Rural and Remote Pharmacy Workforce Development Program

Exploring the relationship between media coverage and participation in entrepreneurship : initial global evidence and research implications

Using a set of variables measured in the Global Entrepreneurship Monitor (GEM) study, our empirical investigation explored the influence of mass media through national culture on national entrepreneurial participation rates in 37 countries over 4 years (2000 to 2003). We found that stories about successful entrepreneurs, conveyed in mass media, were not significantly associated with the rate of nascent (opportunity searching) or the rate of actual (business activities commenced up to 3 months old) start-up activity, but that there was a significant positive association between the volume of entrepreneurship media stories and a nation’s volume of people running a young business (that is in GEM terminology, a business aged greater than 3 but less than 42 months old). More particularly, such stories had strong positive association with opportunity oriented operators of young businesses. Together, these findings are compatible with what in the mass communications theory literature may be called the ‘reinforcement model’. This argues that mass media are only capable of reinforcing their audience’s existing values and choice propensities but are not capable of shaping or changing those values and choices. In the area covered by this paper, policy-makers are committing public resources to media campaigns of doubtful utility in the absence of an evidence base. A main implication drawn from this study is the need for further and more sophisticated investigation into the relationship between media coverage of entrepreneurship, national culture and the rates and nature of people’s participation in the various stages of the entrepreneurial process.